titous wrote:(am I the first to blow the thing on a Due? do I get a prize? )
titous wrote:I stacked a third H-bridge onto the shield and it seems to run OK for now.... I'd still like to hear your thoughts though about whether this is a good idea?
email@example.com wrote:titous wrote:I'm making assumptions though, since on rereading I see you didn't list a part number. Were you using L293Ds (the ones with the built-in flyback protection diodes) or something else?
titous wrote:I'm using the L293Ds that are supplied with the motorshield. I guess I"ll stick with three of them stacked for the time being; I'll be adding some fans as well for active cooling
Do you have an oscilloscope? If so, you might want to put a current sense resistor in line with the output and see exactly how much current is going through the lines. A bundle of ten 1/4 Watt 1 ohm resistors in parallel will be equivalent to a 2-1/2 Watt 100 milliohm current sense resistor, at about a fifth the price. Actual current-sense resistors cost about 50c each, where 1/4 Watt carbon film resistors cost $2 per 200.
If you put that between the shield and your motor, you'll see 100 mV for every amp that goes to the motor.. enough to measure but not enough to change the way anything works. You might just have a motor with lower impedance than the spec sheet says, but you might also see something that suggests a problem with the motor.. more current through one coil than the other, unusually large spikes of flyback current, or something like that.
titous wrote:I do not have an oscilloscope
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